This Phase-II SBIR project is in response to PAR-01-102, "Development of Novel Technologies for In Vivo Imaging." Expanding upon our Phase-I feasibility effort, we propose to construct and validate a complete workstation - the Virtual Navigator- for 3D MDCT-based planning and guidance of bronchoscopic biopsy. Lung cancer is the most common cause of cancer death in the western nations, with the current 5-year survival rate under 15%. Despite continued technological improvements, the lung-cancer mortality rate actually increased 11% between 1979 and 1997. The state-of-the-art procedure for diagnosing and staging lung cancer involves three-dimensional (3D) multi-detector computed-tomography (MDCT) scanning followed by bronchoscopic biopsy. Unfortunately, a high percentage of biopsy procedures are unsuccessful because of the: (1) lack of procedure-planning tools, (2) difficulty in seeing biopsy sites during bronchoscopy, and (3) wide range in physician skill level. The project is driven by the following hypothesis: A computer-based system, enabling 3D MDCT-based procedure planning and follow-on image-guided bronchoscopy, can improve current procedures for the staging, diagnosis, and treatment of lung cancer. The specific aims are as follows. Aim 1: Devise automated methods for MDCT-based procedure planning and image-guided bronchoscopy, thereby enabling more effective biopsy planning and subsequent bronchoscopic biopsy. Aim 2: Prototype a workstation for the interactive planning and guidance of bronchoscopy, thereby providing the physician with a user-friendly system for image-guided bronchoscopy. Aim 3: Perform human studies to establish system functionality and to compare the system to standard practice.These studies, which focus on the bronchoscopic biopsy of suspect mediastinal lymph nodes and peripheral nodules, give a preliminary clinical evaluation and motivate later Phase-Ill and FDA 510K tests. Since the current techniques for diagnosing and staging lung cancer are unsatisfactory, it is critical that accurate tools become available for assessing lung cancer. Further, the impact of therapy and treatment remains largely unchanged over the last twenty years. The image-guided methods featured by the proposed system could make possible the accurate delivery of agents directly into the lung tumor nodule or into involved lymph nodes. With the Virtual Navigator, bronchoscopies can be planned better, more difficult sites can be biopsied, and fewer unsuccessful biopsies will be done. These benefits reduce the need for follow-up procedures, reducing cost and gaining time toward successful treatment, or, stated differently, improve the early diagnosis, staging, and treatment of lung cancer.